The other day I was working on some blog posts, and when I pulled up an image in Preview to edit it, I noticed something odd. It looked like the Preview window was transparent, and that I was seeing a window through it. I thought nothing of it until a few minutes later when I closed a number of open windows on my new 27-inch iMac and noticed that a faint "echo" of those windows was visible on my desktop photo. I realized I was seeing some image persistence.
This is nothing new; back in the days of PCs with cathode-ray tube monitors, it was quite common to see the C: prompt burned into some screens, visible even when the monitor was turned off! But this was a bit of a surprise, since I hadn't experienced image persistence for a long time. And on a brand new 27-inch iMac? Ouch.
I'm guessing that something kept my iMac display from going to sleep, resulting in the "burn in." I usually have the display set to go completely dark after 15 minutes, and had never seen this happen before on this or my previous 27-inch iMac.
Immediately I went to the Apple support communities and searched for image persistence and image retention, and I found that this has been a fairly common issue with the new devices. Not only are iMacs prone to persistent images, but some MacBooks are also seeing the problem. (Mike Rose experienced the image persistence issue specific to the MacBook Pro Retina models with LG panels, and ended up having his screen replaced.) There are a number of people who were so concerned that they brought their devices back to the Apple Store and asked for a replacement, but Apple believes that the problem is common to IPS (in-plane switching) LCD panels and not a real issue.
Apple recommends doing exactly what I had been doing -- setting display sleep after 15 minutes of non-use. Fortunately, they also have instructions on what to do if your get a burned-in image despite using display sleep. In knowledge base article HT5455, "Avoiding image persistence on Apple displays," there's a section on using a screen saver to eliminate a persistent image:
- From the Apple () menu, choose System Preferences, and then click "Desktop & Screen Saver."
- Click the Screen Saver tab.
- Choose a screen saver.
- Set the "Start screen saver" time to be shorter than the "Display sleep" and "Computer sleep" settings in the Energy Saver pane of System Preferences.
- To clear the persistent image, allow the screen saver to run for approximately as long as the image was being displayed.
I had no idea how long the image had been "stuck" on my screen, so I just decided to change the screen saver time to five minutes and the display sleep time to three hours and let the "Flurry" screen saver run for that length of time.
Sure enough, once I returned to my iMac this morning, the annoying persistent images were nowhere to be found. One commenter in the support community suggests that this might be a problem with all IPS LCD panels made by LG, and that this didn't happen with display panels made by Samsung -- a company that Apple seems to want to avoid at this time due to the lawsuit situation going on.
Regardless of the cause, it's refreshing to know that there is a way to correct it and that this does not cause permanent damage to the display. I've changed my iMac settings to go to screen saver after five minutes and to display sleep after 15 minutes, and hopefully I'll never see those persistent images again.
Have any TUAW readers experienced this problem? Did running the screen saver work to eliminate the ghosted images? Let us know in the comments.